C4F7N/CO2混合气体在高压断路器中熄弧特性分析

Analysis on Arc-extinguishing Characteristics of C4F7N/CO2 Gas Mixture in High-voltage Circuit Breaker

摘要:

基于磁流体力学理论，对C4F7N/CO2混合气体和SF6气体的断路器在40 kA短路电流情况下的熄弧特性进行仿真计算，分析两种不同气体的温度特性、灭弧室气体压强。结果表明：相同气压下，9%C4F7N/91%CO2混合气体在燃弧过程中产生的气体压强要比SF6气体产生的压强小，混合气体断路器的燃弧过程中9% C4F7N/91%CO2混合气体熄灭电弧能力相对于SF6气体更弱些；对比电弧等离子体的径向温度，在SF6气体的断路器中，其电弧等离子体的径向温度相较于9%C4F7N/91%CO2混合气体的断路器更高。而在燃弧过程中，相较于SF6气体下的电弧半径，混合气体下的电弧半径更大。当混合气体充气压强提升至0.8 MPa时，温度梯度得到提升，缩减了电弧半径，可有效地扩大径向冷却的作用，使电弧熄灭加速，断路器的熄弧性能能够进一步被提升。

Abstract:

Based on the theory of mangetohydrodynamics, the arc extinguishing characteristics of C4F7N/CO2 mixed gas circuit breaker and SF6 circuit breaker are simulated and computed under 40 kA short-circuit current, and the thermal properties of two gases and the gas pressure in arc-extinguishing chamber are analyzed. The results show that the gas pressure generated by 9%C4F7N/91%CO2 gas mixture during arcing process is smaller than that generated by SF6 gas under the same air pressure, and the arc extinguishing ability of 9%C4F7N/91%CO2 gas mixture during arcing process of mixed gas circuit breaker is weaker than that of SF6 gas. And the radial temperature of SF6 circuit breaker is higher than that of 9%C4F7N/91%CO2 mixed gas circuit breaker, and the arc radius generated during arcing process of 9%C4F7N/91%CO2 gas mixture is larger than that of SF6 gas. When the gas charging pressure of gas mixture is increased to 0.8 MPa, the temperature gradient is improved, the arc radius is reduced, which can efficiently enhance the radial cooling effect, accelerate the extinguishing of arc, and ultimately boost the arc-extinguishing ability of circuit breaker.